The present invention is in the field of fuse holders of the type used to retain automotive-type fuses an vehicle fuse boxes when the fuses are electrically disconnected from their circuits.
Fuses are commonly used in automotive electrical systems to protect circuits against damage caused by overload conditions. Fuses for various circuits are often grouped together at clustered locations where circuit junctions exist in a fuse box, power distribution block, or junction block. It will be understood that the term xe2x80x9cfuse boxxe2x80x9d used hereafter can mean any of these or any equivalent fused circuit junction or housing.
A fuse box is typically a molded plastic casing or housing containing internal fuse-receiving terminals connected to the various circuits by one or more bus bars. A typical automotive fuse has a generally rectangular plastic body with a pair of parallel, blade-like fuse terminals extending therefrom. The outer surface of the fuse box is provided with fuse sockets to allow the fuse terminals to be inserted into electrical engagement with the circuit terminals, thereby completing and fuse-protecting the associated circuit(s).
It is sometimes desirable to temporarily remove certain fuses from their associated circuits, for example to perform maintenance or simply to prevent battery drain. For example, it is good practice to disable the circuits related to airbag systems before working on any system or circuit located near the airbags in order to lessen the likelihood of unintentional activation of the airbags. For another example, clock circuits often maintain a continuous drain on the vehicle battery and should be turned off when the vehicle is being shipped or stored for long periods of time.
Since fuses are easily dropped or lost once removed from the fuse box, attempts have been made to retain fuses in physical association with the box even when disconnected electrically. Devices known as xe2x80x9cfuse holdersxe2x80x9d are therefore often used to connect fuses mechanically to a fuse box in such a manner that the fuse can be moved into and out of electrical engagement with an associated fuse box socket while remaining connected to the fuse box. In particular, the fuse holder securely retains the fuse in a captive, pre-set position relative to the fuse box when the fuse is temporarily electrically disconnected from the socket, thereby maintaining the fuse in position for reinsertion into the socket. The fuse is fixed in place in or on the fuse holder, while the fuse holder typically is slidably connected to the fuse box for movement in the insertion/withdrawal direction of the fuse such that raising and lowering the fuse holder causes the fuse to be withdrawn from and inserted into its socket, respectively.
An example of such a fuse holder is illustrated in FIGS. 1 and 1A for a typical automotive fuse 16 of the type including a main body 16a, a flanged head 16b at the upper end of the main body 16a, and a pair of bayonet connector legs or terminals 16c extending downwardly from the lower end of the body. Body 16a and flanged head 16b are formed of a suitable moldable dielectric material and fuse terminals 16c are formed of a suitable conductive material and are electrically connected within body 16a, in known manner, by a suitable fusible link.
The illustrated fuse box example 12 is formed of a plastic or other moldable dielectric material in a generally rectangular configuration. A plurality of upwardly opening female terminal sockets 12e, f, g and h are provided on the upper side of the fuse box and a pair of guide members 12j and 12k are formed integrally with the upper edge of the fuse box on opposite sides of socket 12h to define vertical guide slots for the legs 14b of a fuse holder 14.
Fuse 16 is inserted into holder 14 through an opening in base 14a of the fuse holder which frictionally engages the sidewalls of fuse body 16a until flanged head 16b abuts base 14a and prevents further insertion. At this point, fuse 16 is fixed in holder 14 to permit the fuse and holder to be raised and lowered as a unit. Slots 14e in the legs 14b of the fuse holder engage pins 121 underneath the slot-defining guide members on each side of the socket, thereby defining the limit of travel of fuse holder 14. In FIG. 1, fuse holder 14 is raised to its maximum extent, such that fuse terminals 16c are withdrawn from socket 12h and therefore electrically disconnected from the associated circuit. FIG. 1A shows fuse holder 14 lowered to insert fuse 16 into socket 12h and thereby connect fuse terminals 16c with the associated circuit terminals in fuse box 12.
Although prior art fuse holders such as the one illustrated in FIGS. 1 and 1A provide positive removal of fuse terminals from their associated circuits, and in some cases further provide an indirect visual indication (by way of the raised state of the fuse holder) to maintenance personnel that the fuse is disconnected from the circuit, they do not provide a direct, positive, immediately-discernable indication that the fuse terminals themselves are fully disconnected. Moreover, prior art fuse holders are typically held in their raised, disconnected state by nothing more than friction or easily overcome detent structure, to enable service personnel to conveniently push them back down and reconnect the fuses with their associated circuits. This creates the possibility of the movable fuse holder being accidentally pushed down and the fuse being reconnected before it is advisable to do so. For example, if someone slips or drops a tool on the fuse holder, the fuse might be prematurely reinserted into its socket.
The invention is a fuse holder assembly for use on a fuse box, comprising a fuse holder and a fuse movably mounted on the fuse holder. The fuse is movable on the fuse holder between a fuse xe2x80x9creadyxe2x80x9d position in which the fuse is aligned for insertion and withdrawal from a socket or terminal on the fuse box, and a xe2x80x9csafexe2x80x9d position in which the fuse is translated and/or rotated in the holder out of alignment with the socket on the fuse box to (1) make it readily visually apparent that the fuse is disconnected, and (2) positively prevent accidental insertion of the fuse terminals into the socket, even if the fuse holder is accidentally driven in the insertion direction.